//============================================================================
//
//   SSSS    tt          lll  lll       
//  SS  SS   tt           ll   ll        
//  SS     tttttt  eeee   ll   ll   aaaa 
//   SSSS    tt   ee  ee  ll   ll      aa
//      SS   tt   eeeeee  ll   ll   aaaaa  --  "An Atari 2600 VCS Emulator"
//  SS  SS   tt   ee      ll   ll  aa  aa
//   SSSS     ttt  eeeee llll llll  aaaaa
//
// Copyright (c) 1995-2012 by Bradford W. Mott, Stephen Anthony
// and the Stella Team
//
// See the file "License.txt" for information on usage and redistribution of
// this file, and for a DISCLAIMER OF ALL WARRANTIES.
//
// $Id: CartCM.hxx 2422 2012-03-16 20:31:31Z stephena $
//============================================================================

#ifndef CARTRIDGECM_HXX
#define CARTRIDGECM_HXX

class System;

#include "bspf.hxx"
#include "Cart.hxx"

/**
  Cartridge class used for SpectraVideo CompuMate bankswitched games.

  This is more than just a cartridge mapper - it's also a "computer" add-on.  
  There's two 8K EPROMs soldered on top of each other.  There's two short
  wires with DB-9's on them which you plug into the two controller ports.
  A 42 or so key membrane keyboard with audio in and audio out, and 2K of RAM.

  There are 4 4K banks selectable at $1000 - $1FFF, and 2K RAM at
  $1800 - $1FFF (R/W 'line' is available at SWCHA D5, so there's no separate
  read and write ports).

  Bankswitching is done though the controller ports
    SWCHA: D7 = Audio input from tape player
           D6 = Audio out to tape player and 4017 CLK
                1 -> increase key column (0 to 9)
           D5 = 4017 RST, and RAM direction. (high = write, low = read)
                1 -> reset key column to 0 (if D4 = 0)
                0 -> enable RAM writing (if D4 = 1)
           D4 = RAM enable: 1 = disable RAM, 0 = enable RAM
           D3 = keyboard row 3 input (0 = key pressed)
           D2 = keyboard row 1 input (0 = key pressed)
           D1 = bank select high bit
           D0 = bank select low bit

    INPT0: D7 = FUNC key input (0 on startup / 1 = key pressed)
    INPT1: D7 = always HIGH input (pulled high thru 20K resistor)
    INPT2: D7 = always HIGH input (pulled high thru 20K resistor)
    INPT3: D7 = SHIFT key input (0 on startup / 1 = key pressed)
    INPT4: D7 = keyboard row 0 input (0 = key pressed)
    INPT5: D7 = keyboard row 2 input (0 = key pressed)

  The keyboard's composed of a 4017 1 of 10 counter, driving the 10 columns of
  the keyboard.  It has 4 rows.  The 4 row outputs are buffered by inverters.

  Bit 5 of portA controls the reset line on the 4017.  Pulling it high will reset
  scanning to column 0.  Pulling it low will allow the counter to be clocked.

  Bit 6 of portA clocks the 4017.  Each rising edge advances the column one
  count.

  There's 10 columns labelled 0-9, and 4 rows, labelled 0-3.

                           Column

    0     1     2     3     4     5     6     7     8     9
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
  | 7 | | 6 | | 8 | | 2 | | 3 | | 0 | | 9 | | 5 | | 1 | | 4 |  0
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
  | U | | Y | | I | | W | | E | | P | | O | | T | | Q | | R |  1
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+     Row
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
  | J | | H | | K | | S | | D | |ent| | L | | G | | A | | F |  2
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+
  | M | | N | | < | | X | | C | |spc| | > | | B | | Z | | V |  3
  +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ +---+ 

  Function and Shift are separate keys that are read by 2 of the paddle inputs.
  These two buttons pull the specific paddle input low when pressed.

  Because the inputs are inverted, a low indicates a pressed button, and a high 
  is an unpressed one.

  The audio input/output are designed to drive a tape player.  The audio output is 
  buffered through an inverter and 2 resistors and a capacitor to reduce the level
  to feed it into the tape player.

  The audio input is passed through a .1uf capacitor and is pulled to 1/2 supply
  by two 20K resistors, then it goes through a hex inverting schmitt trigger to
  square it up.  This then runs into bit 7 of portA.

  This code was heavily borrowed from z26.

  @author  Stephen Anthony & z26 team
  @version $Id: CartCM.hxx 2422 2012-03-16 20:31:31Z stephena $
*/
class CartridgeCM : public Cartridge
{
  public:
    /**
      Create a new cartridge using the specified image

      @param image     Pointer to the ROM image
      @param size      The size of the ROM image
      @param settings  A reference to the various settings (read-only)
    */
    CartridgeCM(const uInt8* image, uInt32 size, const Settings& settings);
 
    /**
      Destructor
    */
    virtual ~CartridgeCM();

  public:
    /**
      Reset device to its power-on state
    */
    void reset();

    /**
      Install cartridge in the specified system.  Invoked by the system
      when the cartridge is attached to it.

      @param system The system the device should install itself in
    */
    void install(System& system);

    /**
      Install pages for the specified bank in the system.

      @param bank The bank that should be installed in the system
    */
    bool bank(uInt16 bank);

    /**
      Get the current bank.
    */
    uInt16 bank() const;

    /**
      Query the number of banks supported by the cartridge.
    */
    uInt16 bankCount() const;

    /**
      Patch the cartridge ROM.

      @param address  The ROM address to patch
      @param value    The value to place into the address
      @return    Success or failure of the patch operation
    */
    bool patch(uInt16 address, uInt8 value);

    /**
      Access the internal ROM image for this cartridge.

      @param size  Set to the size of the internal ROM image data
      @return  A pointer to the internal ROM image data
    */
    const uInt8* getImage(int& size) const;

    /**
      Save the current state of this cart to the given Serializer.

      @param out  The Serializer object to use
      @return  False on any errors, else true
    */
    bool save(Serializer& out) const;

    /**
      Load the current state of this cart from the given Serializer.

      @param in  The Serializer object to use
      @return  False on any errors, else true
    */
    bool load(Serializer& in);

    /**
      Get a descriptor for the device name (used in error checking).

      @return The name of the object
    */
    string name() const { return "CartridgeCM"; }

  public:
    /**
      Get the byte at the specified address.

      @return The byte at the specified address
    */
    uInt8 peek(uInt16 address);

    /**
      Change the byte at the specified address to the given value

      @param address The address where the value should be stored
      @param value The value to be stored at the address
      @return  True if the poke changed the device address space, else false
    */
    bool poke(uInt16 address, uInt8 value);

    /**
      Get the current keybord column

      @return The column referenced by SWCHA D6 and D5
    */
    uInt8 column() const { return myColumn; }

  private:
    // Indicates which bank is currently active
    uInt16 myCurrentBank;

    // The 16K ROM image of the cartridge
    uInt8 myImage[16384];

    // The 2K of RAM
    uInt8 myRAM[2048];

    // RAM read/write state
    uInt8 myRamState;

    // Column currently active
    uInt8 myColumn;
};

#endif
